Whether on a solar-powered calculator or an international space station, solar panels generate electricity using the same principles of electronics as chemical batteries or standard electrical outlets. With solar panels, it's all about the free flow of electrons through a circuit.

To understand how solar panels generate electrical power, it might help to take a quick trip back to high school chemistry class. The basic element of solar panels is the same element that helped create the computer revolution -- pure silicon. When silicon is stripped of all impurities, it makes a ideal neutral platform for the transmission of electrons. Silicon also has some atomic-level properties which make it even more attractive for the creation of solar panels.

Silicon atoms have room for eight electrons in their outer bands, but only carry four in their natural state. This means there is room for four more electrons. If one silicon atom contacts another silicon atom, each receives the other atom's four electrons. This creates a strong bond, but there is no positive or negative charge because the eight electrons satisfy the atoms' needs. Silicon atoms can combine for years to result in a large piece of pure silicon. This material is used to form the plates of solar panels.

Ad

Here's where science enters the picture. Two plates of pure silicon would not generate electricity in solar panels, because they have no positive or negative charge. Solar panels are created by combining silicon with other elements that do have positive or negative charges.

Phosphorus, for example, has five electrons to offer to other atoms. If silicon and phosphorus are combined chemically, the result is a stable eight electrons with an additional free electron along for the ride. It can\'t leave, because it is bonded to the other phosphorus atoms, but it isn\'t needed by the silicon. Therefore, this new silicon/phosphorus plate is considered to be negatively charged.

In order for electricity to flow, a positive charge must also be created. This is achieved in solar panels by combining silicon with an element such as boron, which only has three electrons to offer. A silicon/boron plate still has one spot left for another electron. This means the plate has a positive charge. The two plates are sandwiched together in solar panels, with conductive wires running between them.

With the two plates in place, it's now time to bring in the 'solar' aspect of solar panels. Natural sunlight sends out many different particles of energy, but the one we're most interested in is called a photon. A photon essentially acts like a moving hammer. When the negative plates of solar cells are pointed at a proper angle to the sun, photons bombard the silicon/phosphorus atoms.

Eventually, the 9th electron, which wants to be free anyway, is knocked off the outer ring. This electron doesn't remain free for long, since the positive silicon/boron plate draws it into the open spot on its own outer band. As the sun's photons break off more electrons, electricity is generated. The electricity generated by one solar cell is not very impressive, but when all of the conductive wires draw the free electrons away from the plates, there is enough electricity to power low amperage motors or other electronics. Whatever electrons are not used or lost to the air are returned to the negative plate and the entire process begins again.

One of the main problems with using solar panels is the small amount of electricity they generate compared to their size. A calculator might only require a single solar cell, but a solar-powered car would require several thousand. If the angle of the solar panels is changed even slightly, the efficiency can drop 50 percent.

Some power from solar panels can be stored in chemical batteries, but there usually isn't much excess power in the first place. The same sunlight that provides photons also provides more destructive ultraviolet and infrared waves, which eventually cause the panels to degrade physically. The panels must also be exposed to destructive weather elements, which can also seriously affect efficiency.

Many sources also refer to solar panels as photovoltaic cells, which references the importance of light (photos) in the generation of electrical voltage. The challenge for future scientists will be to create more efficient solar panels are small enough for practical applications and powerful enough to create excess energy for times when sunlight is not available.

Discuss this Article

@Post 132: It is true that most of today's current silicon-based photovoltaic technology is obsolete, or at least not as environmentally friendly as everyone assumes because of the production process, but this should be thought of as a step towards better photovoltaic cells that are quicker, easier and cheaper to manufacture while maintaining efficiency.

This is the case with the newly developed so termed "Organic" photovoltaic technology, which is manufactured using acrylic or glass and rhenium-telluride solution as a semi-conductor. This rhenium-telluride solution is actually just pen ink and as such it will cost very little. Yet this silicon technology was its basis and should therefore be heralded as a forerunner of better things, not criticized because it doesn't fit our current needs in its current form.

Look at post 123. He does point out something most people won't consider. However, he forgets to take note that solar panels pay their way in a couple of years and from then on they continue to generate quite a bit of revenue, unlike coal or gas.

Also, he forgets the aspect of cost of pollution, like how much does CO2 cost and sulfur dioxide that is produced for burning coal. In any case, solar is not completely clean. However, by far it is cleaner then fossil fuels, and will never run out.

Every solar company states that the panels needs to "sense" grid power before they can generate power. That is in case of a grid power outage, the solar panels won't generate power which could injure the power employees. However, in the case of a grid outage, the solar homeowner is left without power.

What's the truth? Sounds like the panels need grid power to work. And there should be an automatic cutoff for this purpose of allowing the homeowner to have power during the daylight hours.

If I want to experiment by creating a 15-watt solar lamp, how and where do I begin? I am a novice to this but really interested. How many solar cells per panel is required and how do I begin with this.

@anon105856: You asked how come the hotter it is, the less energy you can get and that it would make more since you thought that it would work better in the heat. The solar panels work off light, not heat.

Wires are rated for current, and the amount of current a wire can carry is determined by the thickness, and also the temperature as well. This is why you want to have fans and heatsinks for your computer's processor.

At certain sub zero temperatures (I can't remember exactly how low) wires act like superconductors and can use a very thin wire and carry almost infinite current.

For those of you quoting "solar energy is the way to go and will save our world," you have to realize that these solar panels not only cost a boatload of money (already discussed and others agree with me that they will never pay for themselves), they also are not environmentally friendly.

Like everything in this world, solar panels must be produced. From the rock in the ground (silicon) to the highly refined, processed, delicate solar panel you buy to install in your home is many, many industrial steps. Each process required energy (from fossil fuel sources) as well as pollution. There is an article online which sums up a 300-plus page report of a study done on the pollution from making solar cells.

In this report, it states that the amount of pollution generated to "producing the same amount of electricity by fossil fuel generates at least 10 times as much greenhouse gasses." This is assuming the cells last long enough to pay for themselves at current electricity prices.

This report does give some possibility of solar cells to be useful in the long run such as use solar cells to make solar cells, but the initial "cost" both financially and environmentally would be detrimental overall. The amount that we can press the environment to its limits by making these solar cells should be established before the world decides to "make global solar power."

I work for a utility supplying electricity now, and solar cells are rarely considered due to the severe costs. However, no one ever looks at the prior end of how much pollution is required to actually make these cells, and if they are really "eco-friendly."

Great article! Yes, you are right, the electricity generated by solar panel is small compared to the size of panel. Maybe the technology in the future will find a way about how to rapidly increase the electricity power by decrease the number of solar cells.

These things work, and work quietly. We've installed two arrays of 39 panels each, each having it's own 6,000 watt inverter. This is a 12KW system, and it will deliver that in direct sun. They work much better in the cold -- about 125 percent of rated output at 10-20 degrees F, but only 85 percent of rated output at about 90-100 degrees F. Like an overheated motor, they lose efficiency as they heat up.

We've had up to 85KW hours produced in a single day in winter (upstate NY, with snow reflection off the ground). This system is ground-mounted, as you can work on things better and you may be replacing your roof shingles someday, and you don't want them up there if you're shoveling snow off the roof. Also, hardly any roof is facing directly south, which is the best scenario for the panels.

The grants were there in abundance before the government went broke, so we were subsidized well. With the bi-directional meter, the power company can't charge you more for what went in to you than they pay for what went out to them, as there is no record of which way anything went -- just one number on the meter tells who owes who what in terms of KWhours. We have no power bill, there is a surplus of energy going into grid, which is "banked" there until we need it, and are now looking into a plug-in hybrid car that will be charged at home using the sun for our energy source. This can be done, folks, but you need grants to make it worthwhile.

I am an installer for Kenergy solar. The hot water heaters work great. the collectors can heat up over 400 degrees. there is no need for battery systems on your house. put a net meter, which is required by law, in the line. it reads how much is produced. the electric is done over a month. you use 40 kw a month and it produces 39kw you owe for 1kw. if it produces 41kw the electric company owes you for 1kw. they have to pay the same amount they charge.

Also most systems will pay for themselves within 7-10 years. the bad news is this stuff cost a ton of money. --Gary

Am a research student and also very enterprising. is there any way to improve on the PV solar panel to make it profitable enough for commercial investment in Nigeria. if there is any country at all that needs it, it is Nigeria. Population, 150 Million. Total power generating capacity is just 3000MW. Together we can partner to solve this problem an create a big industry in West Africa.

@anon112718: If you have hydrogen binding to silicon only once, then yes it would have a 3+ charge, however there is going to be more then one hydrogen available in the mixture so then there would be 4 hydrogens bonding to the silicon to make an octet, or 0 charge.

Also, from my studies it is very difficult to make any two substances combine that have more than -1 charge per atom. A molecule also has overall charge of 0, 1, or 2 +or- which is many atoms combined.

The more negative or positive charge, the more unstable the molecule becomes. This is why certain substances are mix for the panels because anything else would be unstable or just not even react at all. Hope this clears it up a little.

@anon101366: Yes, you can generate electricity from panels yourself that you can build at home. It takes a bit of work, but it can pay off in a few ways. You can even get tax credits for building home solar systems.

really a nice article. It did help me a lot. i just came downstairs after getting a pair of 100W sharp solar panels, and wanted to know the in depth concepts. bullseye was this article. now i'm pretty much able to show off to the company colleagues. Thanks for letting me do that.

question: if you are hooked in to public utilities don't they by law have to purchase any power you don't use? That's why your power meters run both ways, right? this being the case, why would there be any need for storing the power? It would simply be the power company's problem of storage, correct?

for the guy who said solar power cannot be used for a water heater you are poorly mistaken! i actually built a solar heater for my pool!

it is simply a thin black hose woven back and forth along the roof of my shed that converts the sunlight directly into heat. all that you need then is a small pump to pump water through the hose. it is not super efficient but saves hella money!

This is a question not a comment. I'm planning using a solar panel, to run a 3oow bulb. I'm wondering if i can then use the light produced from the bulb to power the panel once the sun has gone. is this possible or does a solar panel require a particular energy only the sun can provide, or will artificial light be adequate?

So are you telling me I should not take my hard earned money in this economy and get solar panels for my home because it won't be cost effective? wow. i'm a hard working mom and this was depressing. I thought I would help me my kids and the planet all in one big way. Oh well back to reality.

I am doing a science fair project called "At what direction does a solar panel receive the most sunlight in _________?" I think I should
place a solar panel facing east, west, north,and south. Then I am lost. I am sure I know how a solar panel works, but I do not know how I would do the experiment. It would be great if you could help me. Thanks.

I purchased a solar power system to run 3 lamps and a fan. The battery is now dead and I don't want to buy one more. What can I do with this solar panel. How do i know the power capacity the panel is generating? what can i do with the power? Can I attach the power to a stand alone plug point which can be used say to run a table fan? My system is Tata BP Solar, India. It is a 12V system.

There seems to be a wrong impression that once the panels are installed the electricity is free! The real cost of electricity from Photovoltaic panels is in the cost of batteries. Batteries deliver a certain amount of energy (units of electricity)over it's life. The life is limited and depends upon the no. of charge discharge/charge cycle it undergoes and how much the battery is discharged *before* it is set up for the next recharge.

For example a 12V7AmpHour battery will deliver *at most* 8.4 Units of Electricity per 100 Charge/Recharge cycles. The best quality battery under best op. conditions will last~ 800 ChargeDischarge Cycles thus delivering only about 70 units over it's life. In India this battery costs around Rs.1200/-The per unit cost of generation is Rs 16/- as against Rs.4/-. This point needs to be highlighted. Unless the batteries are made efficient only grid linked Systems without intervening batteries seem to be the only answer. Smaller Stand Alone systems are plain uneconomical.

for those of you who believe that it is not cost effective you are right. If you are willing to put 23,000 up front, have 2500 SQ feet of roof space sun 6 hours a day every day. It will take 40 something years it to pay itself off. Considering that the panels are 80% of the cost and the average panel will only last for 25 years at the most this is not a good deal. I am not saying that you should not get it though. It just won't save money.

okay, so let me see if i have all the components right I have to get Silicon which can be easily found in beef jerky in the anti moisture or what you will packets but is easier and more purer in other special stores. Next Phosphorus which can be found in ocean deposits and I am conveniently

located in Nevada which was once an ocean so i can get dirt maybe by a natural open maybe lake or something. Then get Boron which can also be found in stores and then this is the part im not sure about do i melt these together into 2 slabs and wrap copper wiring around the middle of the two of them before putting them on and wrap the remaining copper wiring onto a battery or any other kind of electrical kind of ... source well not a source but something like that i don't know im confused can someone please explain or summarize this paragraph into steps I have resources that i can get the materials i just need to review the steps thank you.

Hot water solar systems work without photo voltaic panels. they simply heat up the water using the greenhouse effect. This hot water (or oil) can be passed through a heat exchanger to drive turbines to generate electricity without the need for any chemistry.

Solar panels are absolutely able to generate electricity for residential needs. It is the price tag for the initial investment that is daunting. A solar panel system that feeds electricity back into the power grid (what you currently receive your electricity from) and produces enough electricity for an entire house will generally cost about $20,000 up front. But, after you subtract rebates and tax credits from various incentive programs, you can get a lot of that money back.

Furthermore, if it provides you with thousands of dollars worth of electricity per year, it's worth the investment over the long term and can actually be a money-maker. A smaller solar panel that is just going to heat your water does not even have to be hooked up to the power grid--it can just be hooked up directly to your hot water tank--and that should be measurably cheaper.

Post your comments

Please enter the code:

Login

Register

Make changes/additions/deletions to the article below, and one of our editors will publish your suggestions if warranted.

Optional: Explanation of your recommended changes

Thank You!

One of our editors will review your suggestion and make changes if warranted.
Note that depending on the number of suggestions we receive,
this can take anywhere from a few hours to a few days.
Thank you for helping to improve wiseGEEK!